Forecasting of auroras is very difficult, even more difficult than making of normal weather forecasts. Auroras are caused by eruptions in the suns surface which are transported towards Earth by a solar wind. By following the eruptions in the sun, we can try to predict the auroral situation 2 or 3 days beforehand. With measuring the solar wind, we can make predictions some hours beforehand. Anyhow, there are so many small details which must be taken into account so that it is impossible to make good prediction according to one measurement, or even according to several measurements.

Nowadays sun, solar wind and our near-space is measured with satellites and different kinds of ground-based instruments. These measurements are available almost real-time and for everyone in the internet. By following these measurements it is possible to say, is it worth of going out to watch or to photograph auroras.

There are several sites in the internet dedicated to these "forecasts". I have collected the sources that I use to one page at http://spaceweb.oulu.fi/~jussila/forecast.html. So far I haven't got time to explain all those measurements (maybe some day...) but I think that those sources give enough information for me to decide is it worth of going out. Results you can see from my photos... ;-)

The Map on the right side shows statistically defined probabilities of seeing auroras in Finland. Probabilities are defined from Finnish Meteorological Institute All-Sky camera chain during several decades.

Some of the major cities are marked on the map, and also Killpisjärvi, which is a small village of about 200 residents, but which has been, and still is, a very important site for auroral research. It is located near the area where auroras occur, auroral oval.

What we can find from the map, is that the probability to see auroras is highest in Kilpisjärvi (75 %). Probability decreases so that in Rovaniemi area probability is roughly 45 %, in Oulu area about 30 % and in Helsinki area only 5 %. 

"So closer you go to North-West part of Finland, more likely you will see auroras."

A dark place without city lights or streetlights! If you are not used to observe auroras, city lights and streetlights will make observing of weak auroras impossible. If auroras are extremely bright, they do are visible also in lighted areas (take a look at pictures aurora_2000_37 - aurora_2000_47, which are taken in our backyard almost at downtown Oulu).

And as open view as possible. Especially to North. Top of a hill (difficult to find in certain areas of Finland...) or open area like field.

Time of the year: Auroras are visible in northern Finland from beginning of September to middle of April. Auroras occur also during summertime, but the night are too light during that period and you can't see auroras at all. Nights in southern Finland are more dark so the period is longer, but at the same time the probability to see auroras so far south is much smaller.

Time of the day: In normal case auroras occur in Finland sector between 21 - 01 in evening, with the maximum around 22 - 23. However, during geomagnetically active times (read: lots of variations and disturbances in near-Earth space which also cause auroras) auroras can be visible during the whole night from 18 - 06.

Changes in auroral activity: Certain cycles can be found from auroral activity. Most important of these are 11-year cycle, 27 day cycle and annual variations.
Suns activity, which is also the main reason of auroras, varies in 11-year cycle. Activity deceases from maximum to minimum in roughly 6 year, and returns to maximum in 5 years. During the maximums auroras are more probable, and during the minimums auroras occur less. This effect especially lot to big auroral storms, when auroras can be seen far south; these are much more probable during suns activity maximum. Currently (November 2000) we are living in middle on maximum time.
The 27 day cycle is caused by Suns rotation. Equatorial region of the Sun rotates around once in 27 days, so if some specific region causes strong auroras, it is possible that it causes auroras again after 27 days.
An annual variation can also be found: Auroras are more probable during autumn and spring equinoxes than during winter solstice. So in that sense, October and March might be good months to go to north.

Might be or might not... :-( The problem is the weather and especially the clouds. I know a group of auroral scientist who spend one month up in the north, and the only night when they saw auroras was the last night. After they had packed all their instruments... On the other hand, I have visited our Kilpisjärvi site sometimes just for one night, and I have sawn a beautiful display. Sad to say, but it is just a matter of luck, or of Mr. Murphy!

Normally, I think, autumn can be (or then not...) very cloudy and better weathers are during winter. Then it can be extremely cold, but we don't care about that, we just want to see auroras! Spring (March) might also be a reasonably good time.